Apparatus for individually steering and driving vehicle wheels

ABSTRACT

This invention provides an apparatus for mounting, driving and steering the wheels of a high mobility wheeled vehicle, such as those used over roadless terrain in tree harvesting operations. Each vehicle wheel is mounted on a rotatable hub which is in turn journaled on the end of a wheel drive housing. The housing is medially pivoted to the wheel suspension structure of the vehicle for steering movements and has a driving motor mounted on the inner end of the housing and connected to the wheel hub through an appropriate gearing system. The pivotal mounting of the drive housing is preferably located at the end of a walking beam arm which is disposed at a substantial horizontal angle with respect to the longitudinal axis of the vehicle to provide clearance for steering movements of the vehicle wheel. The steering motion is imparted to the drive housing by an actuator which is connected between the inner end of the drive housing and the inner end of the walking beam arm.

CROSS-REFERENCE TO RELATED APPLICATION

This application constitutes a continuation-in-part of my co-pendingapplication Ser. No. 842,801, filed Oct. 17, 1977, now U.S. Pat. No.4,153,265.

The wheel suspension mechanism of the off-road vehicle for which thisinvention is particularly suited is disclosed and claimed in myco-pending application Ser. No. 934,459, filed concurrently herewith.

The control circuit for such wheels is disclosed and claimed in myco-pending application Ser. No. 934,457, filed concurrently herewith.

SUMMARY OF THE INVENTION

Generally speaking, this invention relates to self propelled vehiclesused primarily to transport long loads across roadless terrain. Morespecifically, it relates to rubber tired vehicles that have wheelsuspension mechanisms which provide balanced weight between its wheelsand additionally permits adjustment of the steady state position of themain bed frame of the vehicle relative to a longitudinal roll axis topermit compensation for the vehicle position when operating continuouslyon the side of a hill, and also to facilitate unloading the vehicle by aside dumping action in either direction.

In summary, the vehicle comprises an elongated bed frame that forms thebackbone of the vehicle. This frame is balanced on the central portionof modular front and rear wheel assemblies, preferably each having fourquadrilaterally spaced wheels. The quad wheel suspension system isdesigned to provide a freedom of movement of each wheel about mutuallyperpendicular roll and pitch axes that are vertically spaced one abovethe other. The quad wheel assemblies are pivotally mounted on the bed soas to be movable about a roll axis which is parallel to and beneath thelongitudinal axis of the main frame element. On the lower or pitch axisof each quad wheel assembly, two walking beam members, each carrying apair of steerable wheels, are rockably mounted in a balancedrelationship. Thus the walking beams may rock about the pitch axis ofthe quad wheel asssembly while the quad wheel assembly itself may pivotabout the roll axis.

A feature of this invention is the formation of each walking beam in theform of a truncated W-shape in a horizontal plane with a wheel mountedon each extreme end of the two outwardly angled arms of the W. Theutilization of the W-shape provides adequate steering clearance formovements of the wheel, and in accordance with this invention, eachwheel is supported by a drive housing which has its medial portionpivotally mounted to the ends of the W-shaped walking beam members. Thedrive housing carries a driving motor on its inner end and, on its outerend, a wheel mounting hub is rotatably journalled. Within the housing,suitable gearing is provided for connecting the driving motor to thewheel hub.

The steering movements of the wheel are imparted by an actuator which isconnected between the inner end of the wheel drive housing and the baseportion of the angled arm of the walking beam on which the individualwheel is mounted. Thus a triangular relationship is maintained betweenthe end of the walking beam, the wheel drive housing, and the steeringactuator.

The rotational speed, the braking, and the steering of each wheel isindividually controlled in accordance with the method and apparatusdisclosed and claimed in my aforementioned co-pending application, Ser.No. 934,457. A vehicle equipped with this combination of features hasnumerous advantages over prior art road vehicles. The individual controlof the velocity and the turning angle of each wheel permits the vehicleto be manipulated through any selected one of a plurality of unusualmovements or attitudes most of which are completely incapable ofaccomplishment by any vehicle equipped with conventional driving andsteering mechanisms.

Other advantages and objects will become more apparent when thefollowing description is read with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side elevational view of a complete vehicle embodying thewheel suspension mechanism of this invention.

FIG. 2 is a front elevational view of the vehicle of FIG. 1.

FIG. 3 is a plan view of the vehicle of FIG. 1.

FIG. 4 is an enlarged partial perspective view of the suspensionmechanism for the quad wheel assemblies utilized in the vehicle of FIG.1.

FIG. 5 is an enlarged partial perspective view illustrating the rollcontrol linkage for the wheel suspensions incorporated in the vehicle ofFIG. 1.

FIG. 6 is a side elevational view, similar to FIG. 1, of a vehicleincorporating a modified suspension mechanism.

FIG. 7 is a plan view of FIG. 6.

FIG. 8 is an enlarged partial perspective view of the quad wheelsuspension system incorporated in the vehicle of FIG. 6.

FIG. 9 is a partial perspective view illustrating a selected staticposition of the wheel supporting cradles and frame of the vehicle forcontinuous operation along a hillside.

FIG. 10 is an enlarged scale sectional view taken on the plane 10--10 ofFIG. 4.

DETAILED DESCRIPTION OF INVENTION

The vehicle illustrated in the drawings is a transportation vehicle suchas one used for forwarding tree lengths from a harvesting area is aforest to a landing adjacent to a road. Referring particularily to FIGS.1-3 of the drawings, it will be seen that the vehicle 20 is comprised ofan elongated bed frame assembly 21 including load-carrying cradleassemblies 22 adapted to carry a plurality of tree lengths 23. Front andrear quad wheel assemblies 24, 26 are respectively attached to the bedframe assembly 21 by journals so as to be pivotally movable about alongitudinal roll axis disposed parallel to and beneath the bed frameassembly 21. A roll control linkage means 28 interconnects the quadwheel assemblies with each other and with the elongated bed frameassembly so as to control their relative positions during operation overrough terrain. Preferably an engine unit 30 is located at the rear endof the vehicle, and an operator's cab 31 is located at the front end.

The illustrated bed frame assembly 21 comprises an elongated bed frameelement 32 extending lengthwise along the center line of the assembly.The bed frame 32 which serves as the backbone of the vehicle may be arectangular tube. A plurality of rigid bed cross beams 38 extendlaterally outwardly from the bed frame structure in both directions toform the load-carrying cradles 22. Upright side stakes 44 may beprovided on the outer ends of the cross beams. The stakes, along one orboth sides, may be releasably mounted to permit sidewise dumping of theload on either side by appropriately tilting the bed frame assembly 21about the roll axis of the wheel suspension assemblies.

In the drawings it will be noted that the front and rear quad wheelassemblies 24, 26 are substantially identical to one another, so for thesake of brevity, the similar portions will be described with respect toone of them only. Accordingly, attention is directed to FIG. 4 of thedrawings wherein the details of the front squad wheel assembly 24 areillustrated.

The suspension system for the front quad wheel assembly includes a mainpivot block 46 which is pivotally suspended beneath the tubular bedframe 32 between a pair of depending blocks 32a, thus providing pivotalmovement about a longitudinal horizontal roll axis which is parallel toand slightly below the axis of the tubular bedframe 32. Such pivotalmounting is not shown but is entirely conventional. A torquetransmission tube 94 extends rearwardly from the main pivot block 46 andis co-movable therewith about the vehicle roll axis. A similar tube 95extends forwardly from the rear quad wheel assembly and the adjacentends of tubes 94 and 95 are respectively interconnected by a rollcontrol linkage mechanism 28 to be hereinafter described.

The bottom portion of main pivot block 46 is provided with a pair oflaterally projecting horizontal pivot pins 46a which respectivelyprovide pivotal mounting for a pair of walking beams 48 which are ofidentical configuration except that they are mounted in reversedpositions on the pivot pins 46a. Each walking beam 48 is of a generallytruncated W-shaped configuration in plan view including a centraltruncated inverted V-shaped portion 48a defining the bearing for thepivotal mounting on pin 46a and identical angularly disposed arcuate endelements 48b which provide mountings for steerable wheel units 58 of thesquad wheel assemblies. The horizontal angle of elements 48b determinesthe maximum wheel turning angle. The ends of arm portions 48b arebifuracated as indicated at 48c and the bifurcated ends are traversed bya vertical pivot unit 48d which pivotally supports a central cylindricalportion 50a of a wheel spindle housing 50. At its outer end, the spindlehousing 50 terminates in a power driven cylindrical hub 50b to which awheel 58 is rigidly secured in conventional fashion. The inner end ofhousing 50 defines a gear chamber 50c plus a mounting flange 50d formounting an electrically or hydraulically driven reversible motor 54 bywhich the wheel 58 is driven. The gearing mechanism interconnecting thereversible motor 54 with the wheel hub 50b may be entirely conventionaland will be described later. The extreme inner end of wheel spindle ordrive housing 50 is provided with a pair of bifurcated lugs 50e whichpivotally mount the apertured end of a steering actuator 56. The otherend of actuator 56 is pivotally mounted to the bottom portion 48e of thetruncated W-shaped walking beam 48. While actuator 56 may behydraulically operated, I prefer to employ an electrically drivenactuator and hence an actuator motor 57 is mounted on the actuator 56and effects the extension or retraction of actuator 56 to in turn effecta steering motion of the associated wheel 58.

Within housing 50, a suitable power actuated brake (described later) isalso provided.

From the description thus far, it should be apparent that the steeringmovements of the wheels 58 about the respective steering pin units 48dinvolve a much larger turning radius (on the order of two to four feet)than is customarily employed in wheeled vehicles. As is described in myaforementioned co-pending application, Ser. No. 934,457, this largeturning radius is of significant advantage in effecting a lateral bodilydisplacement of the entire vehicle through the combination of limitedsteering, braking and rotational movements of the wheels in a selectedsequence. Obviously, both the wheel driving motors 54 and the steeringactuator motors 57 must have sufficient power to effect the desiredrotation of the wheels and steering of the wheels under the very adverseconditions encountered in off-road operations. Such power may besupplied from a generator (not shown) driven by engine 30.

As previously mentioned, the details of the controls for the rotation,braking and turning of each wheel are described and claimed in myaforementioned co-pending application, Ser. No. 934,457.

From the description thus far, it is also apparent that each quad wheelassembly 24, 26 is suspended relative to the main bed frame element 32in such fashion that the bed frame may pivot relative to the quad wheelassemblies about a roll axis which is parallel to and slightly beneaththe main bed frame element 32. Concurrently, the wheels on each side ofthe quad wheel assembly may freely move in a vertical plane about atransverse horizontal pivot axis defined by the walking beam pivot pin46a. Moreover, due to the "W" shape of each walking beam 48, steeringmovements of each of the wheels up to a thirty degree (30°) angle may beaccomplished in either direction without interference with thesuspension, the main frame or load carrying cradles of the vehicle.

The relative angular movement of the quad wheel assemblies 24, 26 withrespect to each other and to the elongated bed frame assembly 21 isregulated by a roll control linkage 28, centrally located on thevehicle, that causes equal loading to be imposed on each quad wheelassembly, and also causes the bed frame assembly to be rotatedproportionately, preferably one half the total angular displacementbetween the front and rear quad wheel assemblies, as exists at any onetime. Angular displacement between the quad wheel assemblies relative tothe roll axis obviously occurs during operation on uneven terrain orover boulders. The ground under the front quad wheel assembly may belaterally and possibly oppositely inclined to the ground under the rearquad wheel assembly, such as might occur while the vehicle is traversinga ditch at an angle.

Referring now to FIG. 5, the roll control linkage 28 will be describedin greater detail. The rearward end of torque tube 94 and the forwardend of torque tube 95 are suitably journaled in a depending frame block32m and are disposed in spaced co-axially aligned relationshipapproximately in the center of the elongated frame member 32.Immediately above and between the ends of the torque tubes 94, 95, thebase member 32 is provided with a pair of upstanding pivot ears 32fwhich support a pivot pin 32g which traverses the center portion of atransverse frame tilt lever 33. On each end of frame tilt lever 33 alongitudinal connecting lever 35 is mounted for pivotal movement about ahorizontal axis. Additionally, on each end of torque tubes 94 and 95there are respectively rigidly secured primary transverse actuatinglevers 96 and 97 and the ends of these levers are in general verticalalignment respectively with the ends of the connecting levers 35. Aplurality of links 37 are provided respectively having their endsconnected by a universal joint connection to the aligned ends of primarylevers 96 and 97 and the connecting levers 35. Thus, any pivotalmovement of one of the quad wheel assemblies 24, 26 relative to theother will result in a pivoting movement of the associated primary lever96, 97 which in turn effects a tilting movement of the main tilt controllever 33 to shift the position of the main frame 32 approximately onehalf the amount of pivotal displacement of the quad wheel assemblyrelative to the roll axis. Thus a very effective control of themovements of the main frame about the roll axis in response to muchlarger movements of the quad wheel assemblies is achieved and, ineffect, the pivoted lever connection control means 28 provides forbalancing the effects of rotations of the two quad wheel assemblies inopposite directions about the roll axis on the main frame assembly.

Concurrently the roll control linkage effects a transfer of forcesbetween the two quad wheel assemblies to equalize the loading thereofduring movements about the roll axis.

The modification of this invention heretofore described is particularlyuseful in the hauling of trimmed lengths of trees having a total lengthin excess of 60 feet. In some woodland operations, particularly aspracticed in Canada, it is more desirable to employ an off-road vehiclefor bringing out loads of fresh cut whole trees. A load of this typedoes permit some angular shifting of the load supporting cradles as thetransporting vehicle navigates difficult terrain areas.

Referring now to FIGS. 6, 7, 8 and 9, there is shown a modification ofthis invention wherein the load supporting cradles 22 are not rigidlysecured to the elongated tubular frame element 32, but instead comprisea transverse beam 39, which is pivotally mounted to the top surface ofthe tubular bed frame 32. Such pivotal mounting is provided by a pair ofupstanding ears 32b and a pivot pin 32c which traverses the cross-beam39. Each cross-beam 39 is effectively secured for co-movement with themain pivot block 46 of the quad wheel assembly by a pair of parallellinks 40, each of which has a bifurcated end 40a, pivotally connected bya transverse pin 40b to the cross-beam 39, and the other end 40cpivotally connected between a pair of bifurcated ears 46e provided onthe main pivot block 46 and traversed by a pivot pin 46f.

It may be desirable to form the load supporting beams 39 with the outerends inclined upwardly as shown at 39a in FIG. 9, in order to provideadditional clearance for the quad wheel assembly. The important thing isthat as each quad wheel assembly moves about the roll axis to traversethe terrain, a corresponding pivotal movement of the load supportingcradles is imparted by virtue of the parallelogram linkage connection ofthe cross-beams 39 to the main pivot block 46. At the same time, theroll control linkage 28 is still operative to effectively balance outoppositely directed inclinations of the front and rear quad wheelassemblies and thus reduce to a minimum the pivotal movements of thetubular bed frame 32 about the roll axis.

The advantage of this construction is a significant reduction in theheight of the load carrying cradles relative to the main frame, hencelowering the center of gravity of the load.

A further feature of the suspension is the addition to the roll controllever assemblage 28 of a pair of power actuated stabilizing links whichpermit the operator to adjust the static position of the tubular mainframe 32 relative to the roll axis. Referring to FIG. 5, such links maycomprise the power actuated extensible elements 43 which arerespectively connected between the extreme ends of the tilt controllever 33 and a bifurcated end of lateral projection 32k, formed on adepending block 32m, provided on the underside of the tubular bed frame32. As the one stabilizing link 43 is extended by the application ofeither hydraulic or electric power thereto, the other link 43 isretracted so that the net effect is as illustrated in FIG. 9, in thatthe load supporting cradles or cross-beams 39 are shifted laterally andangularly with respect to the roll axis. Thus, the load may bemaintained in a substantially horizontal position, even though thevehicle is being operated continuously on a hillside. The capability foradjusting the static angular position of the load carrying cradlesrelative to the roll axis provides additional stability to the vehicleand hence permits larger loads to be safely carried along a relativelysteep hillside.

An extreme extension of either link 43 can effect the dumping of theload on a selected side of the vehicle.

Referring particularly to FIG. 10, it wll be seen that the wheel drivehousing 50 journals a central shaft 51 which extends through the fulllength of the hollow housing 50. Shaft 51 is driven by motor 54 througha set of co-operating bevel gears 51a and 51b. The outer end of shaft 51drives the sun gear 53a of a planetary gear unit 53 and the wheel hub50b is secured to the planet gear support ring 53c. Wheel hub 50b issuitably journaled on the housing 50 by bearings 50g.

A conventional disc type brake 55 is provided on the inner end of shaft51 and is controlled by suitable hydraulic or electric actuator (notshown).

The pivot unit 48d by which the wheel drive housing 50 is pivotallymounted to the bifurcated ends 48c of the walking beams is alsoillustrated in detail in FIG. 10. The housing 50 is provided with a pairof diametrically disposed cylindrical projections 50f which arerespectively journaled in bearings 48f provided in a hollow cup-shapedsupports 48d which are respectively journaled in the bifurcated ends 48cof the walking beam 48.

Modifications of the preferred embodiments of this invention hereindescribed and illustrated will be apparent to those skilled in the artand it is intended that the scope of the invention be determined solelyby the appended claims.

I claim:
 1. In a self propelled wheel supported vehicle adapted for useover roadless terrain comprising in combination, an elongated bed frame,a wheel suspension structure pivotally secured to said bed frame formovement in a transverse vertical plane about a longitudinal roll axis,a wheel support beam pivotally mounted on said suspension structure formovement in a vertical plane about an axis transverse to said bed frame,said wheel support beam having a base portion defining said pivotalmounting and an arm portion extending angularly outwardly therefrom, (a)an elongated wheel drive housing, means on the outer end of said armportion for pivotally mounting the medial portion of said wheel drivehousing for steering movements, means on said housing for supporting awheel driving motor, a wheel hub rotatably mounted on the outer end ofsaid drive housing, means within said housing connecting said hub andsaid drive motor, and a power actuated extensible and retractable linkpivotally connected at one end to the inner end of said wheel drivehousing and at the other end of said base portion of said wheel supportbeam, whereby the application of power to said link controls thesteering position of a wheel secured to said hub.
 2. The combinationdefined in claim 1 wherein said wheel driving motor is disposed on thetop portion of the inner end of said wheel drive housing.
 3. Thecombination defined in claim 2 wherein said connecting means comprises ashaft extending through said housing, bevel gears connecting said motorto said shaft and planetary gear means connecting said shaft and saidwheel hub.
 4. In a self propelled vehicle adapted for use over roadlessterrain having an elongated bed frame, a quad wheel assembly forsupporting a portion of said bed frame comprising:(1) a primary pivotstructure adapted for mounting on said bed frame for pivotal movementabout a horizontal roll axis parallel to said bed frame; (2) a pair ofwalking beams respectively pivotally secured to the lateral sides ofsaid pivot structure for movement in a vertical plane about a transverseaxis, each said walking beam being generally truncated W-shaped in ahorizontal plane with the pivotal mounting axis passing through thetruncated center portion of the W-shape; (3) means on each of eachW-shaped walking beam for respectively pivotally mounting the medialportion of (a) an elongated wheel drive housing for steering movements;(4) means on said housing supporting a wheel driving motor, the outerend of said housing rotatably supporting a wheel hub driven by saidmotor, and means connecting said motor and said hub, and (5) a poweractuated extensible and retractable link pivotally connected at one endto the inner end of said wheel drive housing and at the other end to thetruncated center portion of the respective truncated W-shaped walkingbeam, whereby the application of power to said link controls thesteering position of a wheel secured to said wheel hub.
 5. Thecombination defined in claim 4 wherein said wheel driving motor isdisposed on the top portion of the inner end of said wheel drivehousing.
 6. The combination defined in claim 5 wherein said connectingmeans comprises a shaft extending through said housing, bevel gearsconnecting said motor to said shaft and planetary gear means connectingsaid shaft and said wheel hub.
 7. In a self-propelled, wheel supportedvehicle adapted for use over roadless terrain comprising, incombination, an elongated bed frame, a wheel suspension structurepivotally secured to said bed frame for movement in a transversevertical plane about a longitudinal roll axis, a wheel support beampivotally mounted on said suspension structure for movement in avertical plane about an axis transverse to said bed frame, said wheelsupport beam having a base portion defining said pivotal mounting an armportion extending angularly outwardly therefrom, and elongated wheeldrive housing, means on the outer end of said arm portion for pivotallymounting the medial portion of said wheel drive housing for steeringmovements, a wheel hub rotatably mounted on the outer end of said drivehousing, means within said housing connecting said hub with a powertransmission source, and a power actuated extensible and retractablelink pivotally connected at one end to the inner end of said wheel drivehousing and at the other end of said base portion of said wheel supportbeam, whereby application of power to said link controls the steeringposition of a wheel secured to said hub.
 8. In a self propelled, wheelsupported vehicle adapted for use over roadless terrain having anelongated bed frame, a quad wheel assembly for supporting a portion ofsaid bed frame comprising:(1) a primary pivot structure adapted formounting on said bed frame for pivotal mounting about a horizontal rollaxis parallel to said bed frame; (2) a pair of walking beamsrespectively pivotally secured to the lateral sides of said pivotstructure for movement in a vertical plane about a transverse axis, eachof said walking beams being generally truncated W-shaped in a horizontalplane with the pivotal mounting axis passing through the center portionof the W-shape; (3) means on each end of each W-shaped walking beam forrespectively pivotally mounting a medial portion of an elongated wheeldrive housing for steering movements; (4) a wheel hub rotatably mountedon the outer end of each said wheel drive housing, and powertransmission means disposed in said housing for rotating said wheel hub,and (5) a power actuated extensible and retractable link pivotallyconnected at one end to the inner end of said wheel drive housing and atthe other end to the truncated center portion of the respectivetruncated W-shaped walking beam, whereby the application of power tosaid link controls the steering position of a wheel secured to saidwheel hub.